In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.

Example Input: Question: What was the age of Raul Boesel the year that Serra qualified for the 1982 Canadian Grand Prix? Passage:Francisco "Chico" Serra (born 3 February 1957 in São Paulo) is a racing driver from Brazil. He won the 1979 British Formula 3 Championship. He participated in 33 Formula One World Championship Grands Prix for Fittipaldi and Arrows, debuting on 15 March 1981. He made 18 starts, not qualifying for the remaining fifteen races, although he ought to have started as the reserve in the 1982 Swiss Grand Prix. However, Ferrari withdrew Patrick Tambay's entry so late that Serra was not allowed to take part. Serra scored one championship point, for finishing sixth in the 1982 Belgian Grand Prix. After qualifying for the 1982 Canadian Grand Prix, Serra and countryman Raul Boesel had a short scuffle. Serra was furious at Boesel for blocking his last flying lap after waving Keke Rosberg by. Boesel denied that this was intentional. Serra made one CART Champ Car start in 1985 at the Portland International Raceway for Ensign Racing but suffered an engine failure.
 Links: a. Arrows Grand Prix International b. Ensign Racing c. Scuderia Ferrari d. Raul Boesel
Example Output: d

Example Input: Question: How old was Sophie Okonedo the year that she appeared as Liz 10, in the episodes "The Beast Below" and "The Pandorica Opens"? Passage:Although Scream of the Shalka continues the narrative of the original 1963–89 programme and the 1996 television film, the show's 2005 revival ignored its events. The series was scripted by veteran Doctor Who writer Paul Cornell, with Richard E. Grant providing the voice for the Ninth Doctor. This performance followed years of rumours that Grant would play the Doctor in a film or new series, and indeed he had appeared as the "Conceited Doctor" in the Comic Relief special Doctor Who and the Curse of Fatal Death in 1999. Grant subsequently went on to appear in the revived television series of Doctor Who as a guest villain in 2012's "The Snowmen" and 2013's "The Bells of Saint John" and "The Name of the Doctor". The Doctor's companion for this adventure, Alison Cheney, was voiced by Sophie Okonedo who a year later would be nominated for an Academy Award for her performance in Hotel Rwanda. She also appeared in the 2010 series of Doctor Who, as Liz 10, in the episodes "The Beast Below" and "The Pandorica Opens". Derek Jacobi reprised his role as the Master in 2007's "Utopia". David Tennant appeared in a cameo role as the Caretaker, later being cast as the Tenth Doctor in 2005.
 Links: a. Tenth Doctor b. Sophie Okonedo c. The Pandorica Opens d. Utopia (Doctor Who)
Example Output: b

Example Input: Question: How many people did Arnstadt command as a company commander of the 6th border company in Dermbach? Passage:In June 1949, Arnstadt registered for service with the Volkspolizei, the police force of the Soviet Occupation Zone, becoming an Anwärter der VP (police cadet) with the Kasernierte Volkspolizei in Gotha. In March 1950, Arnstadt was appointed to the German Border Police (Deutsche Grenzpolizei) in Dermbach, patrolling the Inner German border with West Germany. In 1952, Arnstadt failed his first attempt to become an officer at the police school in Sondershausen. In 1953, his marriage ended in divorce, with his two children Veronika and Uwe staying with the mother, and remarried shortly after. In 1954, Arnstadt passed his officer training at Sondershausen and was appointed the rank of Unterleutnant, and the following year was promoted to lieutenant. Arnstadt functioned as a recruiter for the German Border Police until 1957 when he was appointed as a company commander of the 6th border company in Dermbach. Arnstadt was responsible for a section of the border at Wiesenfeld, a region of Bezirk Suhl in the Rhön Mountains at the westernmost point of the Warsaw Pact. Arnstadt's section contained the highly-strategic Fulda Gap, which aroused the special interest of NATO, and a short distance from the US Army's Observation Post Alpha. Arnstadt moved with his wife to Wiesenfeld and in April 1957 became an unofficial collaborator (Geheimer Informator) of the Ministry for State Security (Stasi) until this relationship was ended fourteen months later. 
 Links: a. Company commander b. Inner German border c. Dermbach d. Kasernierte Volkspolizei
Example Output:
a

